An image forming device which performs image formation of image data read from a document image or image data output from external equipment or a recording medium on a medium such as a recording sheet is prevalent. As an image forming device, a multi-functional peripheral provided with a plurality of functions such as a copying function, a printer function, a facsimile function, a data transmission function and a data filing function is also prevalent. In image forming processing in an image forming device, ink, toner or the like is used for performing image formation.
Currently, as printing ink which is applied to image formation, environmentally friendly type ink is used. For the environmentally friendly type ink, ink in which a part of a petroleum-based organic solvent is replaced with a vegetable-based oil for reducing generation of a volatile organic compound, and the like are used, for example. When scattering in the air, the volatile organic compound is said to generate photochemical oxidants and SPM (suspended particulate matters) and cause health problems such as a respiratory disease and multiple chemical sensitivity. Ink in which the volatile organic compound is decreased is known as the environmentally friendly type ink.
As the environmentally friendly type ink, for example, one called vegetable oil ink is ink in which a specific vegetable oil, ester made from a vegetable oil, or the like is included in a fixed proportion. In addition, one called soy ink is ink in which apart of a conventional petroleum solvent is replaced with a soy oil and a vegetable oil. Moreover, one called W2 (Water Washable) ink is water washable ink which is made from a 100% vegetable oil. Further, one called rice ink is ink in which a rice bran oil is used.
When a printed matter is created using the environmentally friendly type ink as described above, printing a predetermined logo mark indicating that ink in which environmentally friendly type ink is contained as an ingredient is used is performed on the printed matter. For example, logo marks such as a vegetable oil ink mark, a soy ink mark, a W2 ink mark and a rice ink mark are registered as trademarks, and a user who uses each environmentally friendly type ink is to clarify that environmentally friendly type ink is used for a printed matter by printing a logo mark corresponding to ink to be used on the printed matter.
On the other hand, some image forming devices having the copying function are provided with a function for reading information having copy restriction such as a confidential document and information on copyright and the like from a document, and restricting copying concerning these information.
For example, Patent Literature 1 discloses an image forming device which detects a preliminarily registered pattern from image data acquired by a reading portion and replaces a pixel value in an area of the detected pattern with a predetermined pixel value for image formation.
Moreover, Patent Literature 2 discloses an image reading device which detects reading inhibiting information relating to copyright such as a copyright mark and a logo which are added to a document image or the like and adds copy inhibiting information to image data itself that is read therefrom or deletes the image data.